Sentence Problems & Parallelism — Interactive Lesson

The Five Sentence Problems

These are the most common errors in written English. Learn to spot them — and fix them.

① Fragment

An incomplete sentence — missing a subject, a verb, or both. Often a dependent clause left on its own.

❌"Running through the park."(no subject)

❌"Because she was tired."(dependent clause alone)

✓"She was running through the park."

② Run-on Sentence

Two independent clauses joined with no punctuation or connector at all.

❌"I was tired I went to bed."

✓"I was tired, so I went to bed."

③ Comma Splice

Two independent clauses joined with only a comma — no coordinator or semicolon.

❌"I forgot my keys, I had to go back inside."

✓"I forgot my keys, so I had to go back inside."

④ Choppy Sentences

Too many very short sentences in a row. The writing feels jerky and disconnected.

❌"He woke up. He ate. He left."

✓"After waking up and eating, he left."

⑤ Stringy Sentence

Too many clauses chained together with "and" or "and so." The sentence never seems to end.

❌"She got up and she had breakfast and she went to school and she studied all day."

✓"After getting up and having breakfast, she went to school, where she studied all day."

Exercise 1

Identify the Problem

What kind of sentence problem does each example contain?

Question 1 of 6

"Because he didn't study for the test."

Question 2 of 6

"The sun set it grew cold."

Question 3 of 6

"The food was cold, the waiter apologised."

Question 4 of 6

"She woke up. She showered. She dressed. She left."

Question 5 of 6

"We went to the park and we played football and we had a picnic and we watched the sunset and we drove home."

Question 6 of 6

"The role requires creativity, good communication skills, and to work well under pressure."

Exercise 2

Choose the Best Fix

Each sentence below has a problem. Which option fixes it correctly?

Question 1 of 5

Fix the fragment: "Exhausted after the long journey."

Question 2 of 5

Fix the comma splice: "It was raining heavily, we stayed inside."

Question 3 of 5

Fix the run-on: "She was exhausted she fell asleep immediately."

Question 4 of 5

Fix the choppy sentences: "The dog barked. The cat ran. The mouse hid."

Question 5 of 5

Fix the stringy sentence: "She got up and she had breakfast and she got dressed and she left for work."

Parallelism

When you list or compare ideas, every item must have the same grammatical shape.

Parallelism means that words, phrases, or clauses in a list or pair must use the same grammatical form. If you start with a verb ending in -ing, every item in that list should end in -ing. Mixing forms creates a jarring mismatch.

In lists

❌"She enjoys swimming, hiking, and to read."

✓"She enjoys swimming, hiking, and reading."

In pairs

❌"He is tall, athletic, and has intelligence."

✓"He is tall, athletic, and intelligent."

In comparisons

❌"She prefers cooking to eat out."

✓"She prefers cooking to eating out."

💡 Think of parallelism like a set of matching luggage — every piece should look like it belongs to the same set. One odd bag stands out immediately.

🔑 Quick check: Find the list or pair. Read just the items. Ask: are they all the same grammatical shape? If not, make them match.

Exercise 3

Fix the Parallelism

Each sentence has a parallelism error. Rewrite it so all items match grammatically.

Question 1 of 5

"The manager is efficient, organised, and shows great patience."

Hint: Make the third item an adjective like the first two.

Question 2 of 5

"She enjoys reading novels, to watch films, and going for walks."

Hint: Make all three items gerunds (-ing forms).

Question 3 of 5

"The course will teach you to write clearly, think critically, and how to solve problems."

Hint: All three items follow "to" — keep that pattern.

Question 4 of 5

"He said that he was tired, that he needed food, and he wanted to go home."

Hint: All three items should start with "that".

Question 5 of 5

"Her speech was inspiring, thought-provoking, and it moved the audience to tears."

Hint: The third item should be a single adjective like the first two.

Exercise 4

Click the Word That Breaks the Pattern

In each sentence, one item doesn't match the others. Click every word in the odd-one-out item, then press Check.

Sentence 1 of 5